The number of Texans testing positive for cannabis after a traffic accident has gone up over the last few years. Trouble is, there's no quick, reliable test to determine if they're driving while high.
Marijuana is the No. 1 illegal drug in crashes
There are classic signs someone might be driving drunk: weaving, speeding, sudden turns. Sgt. Matthew Dusek says clues that someone is stoned are a bit different.
“Maybe running stop signs, stopping either too soon or too far behind a red light or when the light changes, problems with perception with distances and timing. So very close to a distracted driver on the phone,” he says.
Dusek is a Drug Recognition Expert with Northeast Police Department in the Denton County town of Krugerville. He says most police officers aren’t experienced enough to recognize marijuana impairment. He worries that could be a problem for public safety.
“Alcohol is the No. 1 drug we see in DWIs and crashes,” Dusek says. “The No. 1 illegal drug is marijuana, and it’s becoming increasingly prevalent.”
While fewer people are driving after drinking, more are driving with some sort of marijuana product in their bloodstream, according to the National Highway Traffic Safety Administration. Over the last few years, more and more Texans are testing positive for cannabis after a traffic accident. In 2012 there were nearly 170 crashes where a driver tested positive. By 2016 that increased to nearly 300.
Developing an accurate test
But a positive test doesn’t necessarily mean the driver was high at the time of the accident.
See, to tell if someone is drunk, police can whip out a breathalyzer, no such thing exists for marijuana — at least not yet.
“There is a race to develop urine tests, blood tests, saliva tests, breathalyzers,” Alex Berezow says. He’s a senior fellow at the American Council on Science and Health.
Berezow says the problem with blood and urine tests is that they are not sensitive enough to show whether someone used marijuana five minutes or five days ago. It’s the first few hours after smoking when someone is most likely to be too impaired to drive.
“Whoever gets to market first and can reliably and quickly and easily show a product that a police officer can use on the side of the road is going to have a very substantial market advantage,” Berezow says.
One of the companies developing a marijuana breathalyzer is Hound Labs. Inside the Oakland, California office, CEO Mike Lynn is showing off the breathalyzer. It’s a small, black device with a tube sticking out of it. Lynn says if you blow through it a few times, it’s able to analyze and detect the amount of THC — the active ingredient in cannabis — in someone’s breath in minutes.
“We’re making it ergonomic and quick and easy to use,” Lynn says. “By the end of the year, we will be able to sell to police officers.”
Lynn, an emergency medicine physician and reserve deputy sheriff, gave an earlier version of the device to police in California to try out. The device is now being tested on people in a clinical trial at the University of California, San Francisco.
Professor of laboratory medicine Kara Lynch is in charge of the study. She says there will need to be follow-up research to correlate levels of THC in breath with impairment.
“There’s a lot that’s not known, so there are a lot of studies that can be done,” she says.
The German-based company Drager sells a device that uses saliva to detect THC, but it does not read the level of intoxication.
“The Dräger DrugTest 5000 is currently in field use or pilot programs by law enforcement agencies and Drug Recognition Expert-trained officers in more than a dozen states in the U.S,” a spokesperson for Drager said.
Sgt. Marc Vincent is a police officer in Irving. He says if a breathalyzer or a saliva test is proven to accurately measure trace levels of THC in clinical trials, police officers across the country would be interested.
“There’s several of them trying to come out with the devices,” Vincent said. In addition to Hound Labs, Canada-based Cannabix Technologies says it is in the process of developing a breathalyzer.
“[A marijuana breathalyzer] is certainly an extra tool,” Vincent said. “It would be very beneficial for us.”
A positive test doesn't necessarily mean the driver was high at the time of the accident.
No standard on marijuana intoxication
The problem with all the THC tests in development, Vincent says, is they measure an amount, not a behavior.
“Just because there’s marijuana [in their breath] -- I need to be able to show, prove impairment, that they can’t safely operate a vehicle,” Vincent says.
Unlike alcohol, where a blood alcohol level of .08 indicates impairment -- there’s currently no national standard of intoxication for marijuana. Some states, like Colorado, do enforce a legal limit for THC in blood even though scientists disagree on what amount indicates someone is too high to drive.
While those debates play out, the Texas Transportation Institute is investigating how marijuana use will affect traffic safety across the state.
“Part of the reason to look at it now is to be ahead of the game,” says Jena Prescott, with the Center for Drug and Alcohol Education at Texas A&M
“[We want] to have this good information available to lawmakers when they start making these decisions.”
Decisions about how much marijuana is too much when driving, and potentially, whether or not to legalize recreational use in the state.
